And from Center City to Northeast Philadelphia, SEPTA passengers say they often don't feel safe when high school and middle schoolers are on board.

"When they get out of school, all the cursing, fighting, smoking on the bus, spitting everywhere. I have a 4-year-old son," said Sade Lisojo from Northeast Philadelphia.

SEPTA says this melee Thursday started as an icy snowball fight outside that escalated down to the subway mezzanine and into a brutal attack of students who attend the nearby String Theory School. The fights are sometimes planned, sometimes spontaneous, and usually only last a minute or two with most scattering before police arrive.

In Thursday's fight recorded by several people, more than 50 students looked on, as half a dozen of so students attacked others.